Semiconductor device

ABSTRACT

It is an object of the present invention to fix a semiconductor substrate and a thermal compensating plate in the alloy-free structure. An insulation resin (23) for side wall protection fixed on the outer periphery of a semiconductor substrate (1) and a projection (6a) inside an insulation tube are bonded with an adhesive agent (24) to restrict movements of the semiconductor substrate (1) in the radial direction. A thermal compensating plate (3) and a main electrode (5) are normally positioned with each other by a screw pin (32). A fixing ring (30) having resin or metal such as aluminum or the like which fits to the outer peripheral side of the main electrode (4) and the outer peripheral side of the thermal compensating plate (2) and the edge part of the upper main surface thereof restricts movement of the thermal compensating plate (2) in the radial direction. Further, a spring (31) interposed between a flange portion (4c) of the main electrode (4) and the fixing ring (30) presses and energizes the thermal compensating plates (2, 3) and the semiconductor substrate (1) against the main electrode (5). Since the free movements of the semiconductor substrate and the thermal compensating plates is restricted, the semiconductor substrate can be prevented from damage.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to semiconductor devices, and particularlyto improvement in the structure for positioning semiconductor substratesand the structure for positioning parts for transmitting light signalsfunctioning as trigger signals.

2. Description of the Background Art

FIG. 9 is a front sectional view showing an example of a pressurecontact type thyristor of the light trigger type which is one ofconventional pressure contact type semiconductor devices. As shown inFIG. 9, in this pressure contact type thyristor, a thermal compensatingplate 3 formed of material having its coefficient of thermal expansionapproximate to that of a semiconductor substrate 1 is attached to thelower main surface of the semiconductor substrate 1 having the thyristorelements built therein. This thermal compensating plate 3 and thesemiconductor substrate 1 are soldered to each other with soldermaterial such as aluminum or aluminum-silicon.

The thermal compensating plate 3 is subjected to the shaping processingat its end surface, and also subjected to the chemical treatment, andfurther, the surface treatment agent is applied thereto. A mainelectrode 5 formed of copper abuts on the lower main surface of thethermal compensating plate 3. This main electrode 5 is silver-solderedto an insulation tube 6 formed of ceramics through a metal plate 8.

Another thermal compensating plate 2 is provided on the upper mainsurface of the semiconductor substrate 1. This thermal compensatingplate 2 is made to adhere to the upper main surface of the semiconductorsubstrate 1 with silicone rubber, for example. A main electrode 4 formedof copper abuts on the upper main surface of the thermal compensatingplate 2. The main electrode 4 is silver-soldered to the insulation tube6 formed of ceramics through a metal plate 7.

The insulation tube 6 establishes insulation between the two mainelectrodes and forms a housing accommodating the semiconductor substrate1 and the like inside together with the main electrodes 4, 5 and themetal plates 7, 8. A metal tube 11a for guiding light signals and ametal tube 11b functioning as an exhaust spigot are attached to theinsulation tube 6 by silver soldering.

A light guide 10 for guiding the light signals inputted from outside toa light receiving portion is inserted in the metal tube 11a. This lightguide 10 airtightly adheres to the metal tube 11a with an adhesive agentsuch as solder or glass with low melting point. The light receivingportion 1a is provided at the center part of the semiconductor substrate1, to which the light emitting end of the light guide 10 is fixedlycoupled.

The light guide 10 and the light receiving portion 1a are bonded byusing an optical coupling agent 21 such as silicone rubber or the likewhich has optical transparency, refractive index approximate to that ofthe light guide 10, and buffering effect. The light guide 10 is fixed toprevent a decrease of the coupling efficiency of the opticaltransmission system to transmit optical power as large as possible tothe light receiving portion 1a.

The inside of the above-described housing is made airtight, and inertgas is sealed therein. With the semiconductor substrate 1, the thermalcompensating plate 2, and the thermal compensating plate 3 accommodatedin the housing, the end surface of the metal plate 8 silver-soldered tothe main electrode 5 and the insulation tube 6 are finally welded, andthe gas remaining inside is exhausted through the metal tube 11b andreplaced by inert gas, and then the end portion of the metal tube 11b isarc-welded to realize the airtightness of the housing and seal of theinert gas.

The light signal is transmitted through an external optical fiber (notshown) from an external LED, LD, etc. (not shown), which serves as alight source, and then guided to the light entering end of the lightguide 10 through an external connector (not shown). The light guide 10changes the direction of progress of the incident light signal by 90°and irradiates the light receiving portion 1a from the light emittingend facing to the light receiving portion 1a of the semiconductorsubstrate 1.

The semiconductor substrate 1 converts the light signal into thephotoelectric current in the vicinity of the light receiving portion 1aand amplifies the photoelectric current to establish a conductive statebetween the two main electrodes 4 and 5. That is to say, this deviceperforms switching operation triggered by the light signals.

FIG. 10 is a front sectional view of another conventional pressurecontact type thyristor disclosed in Japanese Patent Laying-Open No.4-120772. This device is a GTO (Gate Turn Off) thyristor of the electrictrigger type having the so-called alloy-free structure, in which thesemiconductor substrate 1 and the thermal compensating plates 2 and 3are not soldered.

This device is different from the device shown in FIG. 9 in that thesemiconductor substrate 1 and the thermal compensating plates 2, 3 arenot soldered, so that heat distortion resulted from difference incoefficients of thermal expansion among them, i.e., the warptransformation caused by the temperature change is suppressed to aboutseveral μm. Accordingly, as uniform pressure welding is realized betweenthe thermal compensating plates 2, 3 and the main electrodes 4, 5, it isadvantageous in that the thermal and electric contact resistances arelow in the pressure contact.

In FIG. 10, the same characters are allotted to the same parts as thosein the device shown in FIG. 9, and detailed descriptions thereof are notrepeated. In the device shown in FIG. 10, the semiconductor substrate 1is subjected to the shaping processing at its end surface, and then tothe chemical treatment, and further, the surface treatment agent isapplied thereto. Stepping processing is applied to the end surface ofthe thermal compensating plate 3, and the semiconductor substrate 1 ismade to adhere to the step portion with silicone rubber 23 or the like.The adhesion is made only at the end, so that thermal distortion doesnot occur in the thermal compensating plate 3 as described above.

Furthermore, similarly to the device of FIG. 9, the main electrode 4,the metal plate 7 and the metal tube 11 are silver-soldered to theinsulation tube 6 formed of ceramics to form a housing. A groove isformed in the center portion of the bottom of the main electrode 4abutting on the thermal compensating plate 2, in which groove a guidering 50 formed of an insulating material is inserted. An output end of agate lead line 60 transmitting the electric trigger signals isincorporated in this guide ring 50, and its one input end passes throughthe metal tube 11.

The guide ring 50 presses and energizes the output end of the gate leadline 60 against the upper main surface of the semiconductor substrate 1with the elastic force of a spring 31. The portion between the input endand the output end of the gate lead line 60 is covered with aninsulating tube 61. The insulating tube 61 prevents electric contact ofthe gate lead line 60 with the main electrode 4.

Similarly to the device of FIG. 9, the housing is made airtight insideand inert gas is sealed therein. With the semiconductor substrate 1, thethermal compensating plate 2 and the thermal compensating plate 3accommodated in the housing, the end surface of the metal plate 8silver-soldered to the main electrode 5 and the insulation tube 6 arewelded at last, and the gas remaining inside is exhausted through themetal tube 11 and replaced by the inert gas, and then the end of themetal tube 11 is arc-welded to realize the airtightness of the housingand sealing of the inert gas.

As the conventional semiconductor devices are configured as discussedabove, they have such problems as listed below.

First, as the semiconductor substrate 1 and the thermal compensatingplate 3 are bonded by means of the solder material in the conventionalpressure contact type semiconductor device, it has been a problem thatwarp transformation is caused in the coupled body of the semiconductorsubstrate 1 and the thermal compensating plate 3 by the difference inthermal shrinkage resulted from the difference in the thermal expansioncoefficients of the two when they are cooled after the alloy process,resulting in uneven contact surfaces between the semiconductor substrate1 and the main electrodes 4, 5 to decrease the yield of the device.Particularly, with the recent increase of calibers of the devices, thisproblem is becoming more serious.

As a countermeasure, such devices as have the alloy-free structure inwhich the semiconductor substrate 1 and the thermal compensating plate 3are not alloyed as described above are appearing. However, thisconventional device of the alloy-free type involves a problem that thesemiconductor substrate 1 and the thermal compensating plate 3 move inthe radial direction or in the axial direction when assembled ortransported because they are not fixed and cause damage or thesemiconductor substrate 1. Particularly, the devices of the opticaltrigger type involve the problem that the light guide 10 may be damaged,or the relative position of the light receiving portion 1a of thesemiconductor substrate 1 and the light emitting end of the light guide10 may be displaced, so that the light signals are not transmitted tothe semiconductor substrate 1, with the result that the device does notoperate adequately.

Second, in the conventional light trigger semiconductor device, the lossheat generated in the semiconductor substrate 1 by the passage ofcurrent is transmitted to outside through the thermal compensatingplates 2, 3 and the electrodes 4, 5 to prevent the semiconductorsubstrate 1 from being overheated. However, a notch 4a is formed in themain electrode 4 to introduce the light guide 10 for transmitting thelight signals, and a groove with certain volume is formed in the centerportion of the bottom of the main electrode 4 when a guide ring or thelike is used for normally positioning the output end of the light guide10 to the light receiving portion 1a of the semiconductor substrate 1.The conventional device has a problem that the transmission efficiencyof the loss heat decreases more as the volume of the notch 4a and thegroove becomes larger.

Third, when assembling the conventional light trigger semiconductordevice, the light guide 10 is introduced, and then, welding is performedbetween the metal plate 7 previously fixed to the periphery of the mainelectrode 4 and the insulation tube 6 to fixedly join the main electrode4 to the insulation tube 6. Accordingly, it has been a problem that themain electrode 4 turns when temporarily assembled in the process beforethe welding is finished and the notch 4a touches the light guide 10 togive damage to the light guide 10.

Fourth, as both the light entering end and the light emitting end of thelight guide 10 are fixed in the conventional light trigger semiconductordevice, there is a possibility of damaging the light guide 10 by theexpansion and shrinkage of parts caused by repeated temperature change.In addition, it is a problem that the yield of the device decreases inthe process of incorporating the light guide 10 into the device, i.e.,in the process of adhesion using solder and realizing the airtightstate.

Fifth, as the conventional pressure contact type semiconductor device ofthe alloy-free structure is constructed as shown in FIG. 10, the end ofthe semiconductor substrate 1 must be stuck to the thermal compensatingplate 3 so that the semiconductor substrate 1 and the thermalcompensating plate 3 will not slip off from the predetermined relativeposition, and this process is not easy. Furthermore, as the siliconerubber or the like used for adhesion has fluidity, it may flow inbetween the semiconductor substrate 1 and the thermal compensating plate3.

SUMMARY OF THE INVENTION

According to the present invention, a pressure contact typesemiconductor device comprises a semiconductor substrate, a thermalcompensating plate in alloy-free contact with the semiconductorsubstrate, and a main electrode in contact with the thermal compensatingplate, wherein the thermal compensating plate and the main electrode fitto different ends of a pin to be positioned relatively to each other.

According to the pressure contact type semiconductor device of thepresent invention, since the main electrode and the thermal compensatingplate in contact with each other fit to the common pin to be fixed,damage of the semiconductor substrate caused by displacement thereof intransportation and the like before use of the device can be prevented.

Preferably, in the pressure contact type semiconductor device accordingto the invention, the thermal compensating plate and the main electrodefit to the pin only at approximate center positions of the respectivecontact surfaces.

According to the pressure contact type semiconductor device of theinvention, since the thermal compensating plate and the main electrodefit to the common pin only at a single position at the approximatecenter thereof, positional slipping off in the radial direction can beprevented with the simplest structure.

In another aspect of the present invention, a pressure contact typesemiconductor device comprises a semiconductor substrate and aninsulation tube surrounding the semiconductor substrate, wherein thesemiconductor substrate is fixed to an inner wall of the insulationtube.

In the pressure contact type semiconductor device of the invention, asthe semiconductor substrate is fixed to the insulation tube, there is nopossibility that the semiconductor substrate moves to abut on the innerwall of the insulation tube or the like to be damaged.

Preferably, in the pressure contact type semiconductor device accordingto the invention, a projection projecting inwardly is formed on theinner wall of the insulation tube and the semiconductor substrate isfixed to the projection.

In the pressure contact type semiconductor device of the invention, asthe semiconductor substrate is fixed to the projection formed on theinner wall of the insulation tube, the semiconductor substrate can beeasily fixed.

Preferably, in the pressure contact type semiconductor device accordingto the invention, the semiconductor substrate is fixed to the projectionby using an adhesive agent.

In the pressure contact type semiconductor device of the invention, asthe semiconductor substrate is fixed to the projection by using theadhesive agent, the semiconductor substrate can be fixed more easily.

Preferably, in the pressure contact type semiconductor device accordingto the invention, the semiconductor substrate is fixed to the projectionthrough a protection resin provided on a periphery of the substrate.

In the pressure contact type semiconductor device of the invention, asthe semiconductor substrate is fixed to the projection through the resinfor protection, damage to the semiconductor substrate caused byvibration, impact and the like applied from outside can be prevented.Preferably, in the pressure contact type semiconductor device accordingto the invention, the projection is formed on entire periphery of theinner wall.

In the pressure contact type semiconductor device of the invention,since the projection is formed all around the entire periphery of theinner wall of the insulation tube, the semiconductor substrate is stablyfixed.

Preferably, in the pressure contact type semiconductor device accordingto the invention, inside of the insulation tube accommodating thesemiconductor substrate is airtight from outside and a through hole isformed in the projection.

In the pressure contact type semiconductor device of the invention, asthe inside of the insulation tube is made airtight from outside, theinert gas can be introduced into it to improve the stability ofoperation of the semiconductor substrate and the like and to extend thelife-time thereof. Furthermore, as the through hole is formed in theprojection, the two regions inside the insulation tube partitioned bythe semiconductor substrate communicate with each other through thethrough hole when the semiconductor substrate is bonded to theprojection. Accordingly, unnecessary gas remaining inside can beexhausted from both of the two regions through an exhaust spigotprovided only at one position of the insulation tube before the devicehas been assembled, and an inert gas can be substituted for the same.

In another aspect of the present invention, a pressure contact typesemiconductor device comprises a semiconductor substrate and aninsulation tube surrounding the semiconductor substrate, wherein thesemiconductor substrate is fixed to an inner wall of the insulation tubethrough a protection resin.

In the pressure contact type semiconductor device of the invention,since the semiconductor substrate is fixed to the inner wall of theinsulation tube through the resin for protection, there is nopossibility of the semiconductor substrate moving to abut on the innerwall of the insulation tube or the like to be damaged. Also, damage tothe semiconductor substrate caused by vibration, impact, etc. appliedfrom outside can be prevented.

In another aspect of the present invention, a pressure contact typesemiconductor device comprises a semiconductor substrate, a mainelectrode pressure-contacted to the semiconductor substrate, and acontrol signal transmission path for transmitting a control signal tothe semiconductor substrate, wherein the main electrode defines a grooveaccommodating the control signal transmission path and the shape of thegroove has its opening width increasing from a deeper portion toward anopening portion.

In the pressure contact type semiconductor device of the invention, asthe groove accommodating the control signal transmission path has ashape which has its width of opening increasing from the deeper portiontoward the opening portion, such as a tapered shape, accommodation ofthe control signal transmission path is easy and the volume of thegroove can be small. Accordingly, the loss heat produced in thesemiconductor substrate can be effectively radiated to outside.

The present invention is also directed to a light trigger typesemiconductor device. According to the present invention, the lighttrigger type semiconductor device comprises a semiconductor substrate,an insulation tube surrounding the semiconductor substrate and a lightguide transmitting a light signal to the semiconductor substrate,wherein a part of the light guide is accommodated in a tubular body andattached to the insulation tube.

In the light trigger type semiconductor device of the invention, since apart of the light guide which is easy to be damaged is accommodated in atubular body and attached to the insulation tube, the light guide is notlikely to be damaged.

Preferably, in the light trigger type semiconductor device according tothe invention, the tubular body projects inside the insulation tube andthe light guide is inserted into the tubular body with play.

In the light trigger type semiconductor device of the invention, as apart of the light guide is inserted into a tubular body projectinginside the insulation tube, it can be prevented that other parts such asthe main electrode arranged inside the insulating tube directly abut onthe light guide. Further, as the light guide is inserted into thetubular body with play, impact will not be transmitted to the lightguide if other parts abut on the tubular body. Accordingly, damage ofthe light guide can be prevented particularly when assembling thedevice.

Preferably, in the light trigger type semiconductor device according tothe invention, a part of the light guide is inserted into the tubularbody through an elastic tubular body.

In the light trigger type semiconductor device of the invention, since apart of the light guide is inserted into the tubular body through theelastic tubular body, damage of the light guide caused by vibration,impact and the like applied to the device from outside and transmittedto the light guide can be prevented.

In another aspect of the present invention, a light trigger typesemiconductor device comprises a semiconductor substrate, an insulationtube surrounding the semiconductor substrate and a light guidetransmitting a light signal to the semiconductor substrate, wherein apart of the light guide is attached to the insulation tube through anelastic tubular body.

In the light trigger type semiconductor device of the invention, as apart of the light guide is attached to the insulation tube through theelastic tubular body, damage of the light guide caused by vibration,impact and the like applied to the device from outside and transmittedto the light guide can be prevented.

In another aspect of the present invention, a light trigger typesemiconductor device comprises a semiconductor substrate, a light guidetransmitting a light signal to a light receiving surface of thesemiconductor substrate and a guide ring fixed on the semiconductorsubstrate to surround the light receiving surface, wherein a lightemitting end of the light guide is inserted into the guide ring.

In the light trigger type semiconductor device of the invention, as thelight emitting end of the light guide is inserted into the guide ring,the light emitting end of the light guide can be easily positioned to anadequate position with respect to the light receiving surface.

Preferably, the light trigger type semiconductor device according to theinvention comprises the guide ring as a first guide ring, and furthercomprises a second guide ring into which the light emitting end of thelight guide is inserted, wherein the light emitting end of the lightguide is inserted in the first guide ring with play and the second guidering fits to the outer periphery of the first guide ring.

In the light trigger type semiconductor device of the invention, as twokinds of guide rings are used, these guide rings can be fitted to eachother to easily position the light emitting end.

Preferably, in the light trigger type semiconductor device according tothe invention, the light emitting end of the light guide is fixed insidethe guide ring by an adhesive optical coupling agent put inside theguide ring.

In the light trigger type semiconductor device of the invention, sincethe light emitting end of the light guide is fixed in the guide ringwith the optical coupling agent having adhesion, the thermal stressesare absorbed by the optical coupling agent. Further, transmission oflight signals from the light emitting end of the light guide to thelight receiving surface of the semiconductor substrate can be madeefficiently.

In another aspect of the present invention, a pressure contact typesemiconductor device comprises a semiconductor substrate, a thermalcompensating plate in contact with the semiconductor substrate and amain electrode in contact with the thermal compensating plate, and itfurther comprises a ring which fits to outer peripheries of both of thethermal compensating plate and the main electrode.

In the pressure contact type semiconductor device of the invention, thethermal compensating plate is restricted to the main electrode by thering. Accordingly, there is no possibility of the thermal compensatingplate sliding along the semiconductor substrate to give damage to thesemiconductor substrate.

Preferably, the pressure contact type semiconductor device according tothe invention further comprises an elastic body interposed between themain electrode and the ring, wherein the ring engages with an edgeportion of a surface, abutting on the main electrode, of the thermalcompensating plate, and the ring is pressed and energized against thethermal compensating plate by an elastic force of the elastic body.

In the pressure contact type semiconductor device of the invention,since the ring engages with the edge portion of the surface of thethermal compensating plate which abuts on the main electrode and thering is pressed and energized against the thermal compensating plate bythe action of the elastic body, damage of the semiconductor substratecaused because the semiconductor substrate and the thermal compensatingplate individually vibrate due to impact etc. applied from outside.

Accordingly, it is an object of the present invention to provide asemiconductor device in which a semiconductor substrate and a thermalcompensating plate are fixed, heat generated inside the device iseffectively transmitted to outside, damage of a light guide isprevented, and the light guide is easily assembled into the device.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front sectional view of a pressure contact typesemiconductor device in the preferred embodiment.

FIG. 2 is a fragmentary enlarged front sectional view of the device inthe preferred embodiment.

FIG. 3 is a fragmentary enlarged front sectional view of the device inthe preferred embodiment.

FIG. 4 is a fragmentary plan view of the device in the preferredembodiment.

FIG. 5 is a front sectional view of the main electrode in the preferredembodiment.

FIG. 6 is a bottom view of the main electrode in the preferredembodiment.

FIG. 7 is an enlarged front sectional view of the vicinity of the lightintroducing window in the preferred embodiment.

FIG. 8 is an enlarged front sectional view of the vicinity of the lightreceiving surface in the preferred embodiment.

FIG. 9 is a front sectional view of a conventional pressure contact typesemiconductor device.

FIG. 10 is a front sectional view of another conventional pressurecontact type semiconductor device.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of the present invention will now be describedreferring to the figures. FIG. 1 is a front sectional view of a pressurecontact type thyristor of the light trigger type in this preferredembodiment. In this device, a light receiving portion 1a is provided atthe center portion of the upper main surface of the semiconductorsubstrate 1. A light emitting end of a light guide (control signaltransmission path) 10 for transmitting light signals (control signals)inputted from outside faces to this light receiving portion 1a.

A thermal compensating plate 2 and a thermal compensating plate 3 abuton the upper main surface and the lower main surface of thesemiconductor substrate 1, respectively. These thermal compensatingplates 2 and 3 are not alloyed to the semiconductor substrate 1 bysoldering or the like, but they are pressure-contacted to the mainsurfaces of the semiconductor substrate 1 in the so-called alloy-freemanner.

The thermal compensating plates 2 and 3 are held between the mainelectrodes 4 and 5, respectively. These main electrodes 4 and 5 arefixed to an insulation tube 6 formed of ceramics, for example, throughcircular ring like metal plates 7 and 8, respectively. The insulationtube 6 has an outward projection, or a concave·convex portion forsuppressing creeping discharge on its outer periphery. The insulationtube 6 also has a projection 6a projecting inwardly along its innerperiphery.

The thermal compensating plate 3 and the main electrode 5 are normallypositioned by a screw pin (pin) 32. That is to say, a through hole isprovided at the center of the thermal compensating plate 3 and a tappedhole is provided at the center of the corresponding main electrode 5,where the screw 32 which threadingly engages the tapped hole gets intothe through hole of the thermal compensating plate 3 to restrictmovement of the thermal compensating plate 3 in the radial direction. Asthe thermal compensating plate 3 does not move in the radial direction,it does not give damage to the semiconductor substrate 1. Furthermore,it does not damage nor move insulation resin (resin for protection) 23,described later, attached to the outer periphery of the semiconductorsubstrate 1, either.

Moreover, the screw pin 32 threadingly engages the tapped hole of themain electrode 5 not to move in the axial direction of the through hole,so that it will not collide with the semiconductor substrate 1 to damageit. Also, the screw pin 32 prevents the movement in the radial directionin the thermal compensating plate 3 with the simplest structure ofengaging only at the center portion of the thermal compensating plate 3and the main electrode 5.

A pin which has no screw can be used instead of the screw pin 32.Examples thereof are shown in FIG. 2 and FIG. 3. These FIG. 2 and FIG. 3are fragmentary enlarged sectional views of the vicinity of the centerpart of the thermal compensating plate 3 shown in FIG. 1.

In the example shown in FIG. 2, a hole having a bottom is provided inplace of the through hole at the center of the thermal compensatingplate 3, and a hole having a bottom similar to that of the thermalcompensating plate 3 is provided in place of the tapped hole at thecenter of the corresponding main electrode 5. A pin 33 having no screwis used in place of the screw pin 32, and this pin 33 gets into the bothholes having bottoms to realize normal position of the thermalcompensating plate 3 and the main electrode 5.

In this example, the movement of the thermal compensating plate 3 in theradial direction is also restricted, so it will not damage nor move theinsulating resin 23 attached on the outer periphery of the semiconductorsubstrate 1. Furthermore, as the hole provided in the thermalcompensating plate 3 is not a through hole but a hole having a bottom,the pin 33 will not hit the semiconductor substrate 1 to give damage tothe semiconductor substrate 1.

In the example shown in FIG. 3, the pin 33 not only gets in the holewith the bottom of the main electrode 5, but it is also soldered with asolder material 25. Accordingly, the pin 33 will not move in the axialdirection of the hole, so that the hole provided in the thermalcompensating plate 3 may be a through hole as shown in FIG. 3. Also,instead of soldering the pin 33 to the main electrode 5, it may besoldered to the thermal compensating plate 3. Any of these structurescan produce the same effects as the structure using the screw pin 32.

Referring to FIG. 1 again, a fixing ring 30 fitting to the outerperipheral surface of the main electrode 4, and the outer peripheralsurface and the edge portion of the upper main surface of the thermalcompensating plate 2 restricts the movement of the thermal compensatingplate 2 in the radial direction. Accordingly, the thermal compensatingplate 2 will not slide along the semiconductor substrate 1 to givedamage to the semiconductor substrate 1 or to damage the insulationresin 23. The fixing ring 30 is formed of resin or metal such asaluminum or the like.

The main electrode 4 has a flange portion 4c projecting outwardly at theupper end of its outer peripheral surface. A spring (elastic body) 31such as a spring coil, a corrugated ring spring, or a belleville springis interposed between the lower surface of this flange portion 4c andthe upper end of the fixing ring 30.

The fixing ring 30 presses and energizes the thermal compensating plates2 and 3 and the semiconductor substrate 1 against the main electrode 5with the elastic force of this spring 31. Accordingly, there is nopossibility of the semiconductor substrate 1 and the thermalcompensating plates 2 and 3 individually moving in the axial directiondue to the vibration caused by the spring action of the metal plates 7and 8 to damage the semiconductor substrate 1 and the light guide 10.Also, such a problem as damaging bonding between the light emitting endof the light guide 10 and the light receiving portion 1a of thesemiconductor substrate is avoided, and the decrease in the yield of thedevice is suppressed. At the same time, the action of the spring 31makes the surface contact of the thermal compensating plates 2, 3 andthe semiconductor substrate 1 uniform to improve the heat radiatingcharacteristics and the like.

The movement of the semiconductor substrate 1 in the radial direction isrestricted by bonding the insulation resin 23 for side wall protectionadhering to the periphery of the semiconductor substrate 1 and theprojection 6a in the insulation tube with the adhesive agent 24. As themovement of the semiconductor substrate 1 in the radial direction isrestricted, damage caused by the semiconductor substrate 1 slidingbetween the thermal compensating plates 2 and 3, or the damage caused byabutting on the inner wall of the insulation tube 6 can be avoided.Furthermore, since it is fixed through the insulation resin 23,vibration and impact applied from outside are absorbed by thisinsulation resin 23. Accordingly, damage of the semiconductor substrate1 due to the vibration and impact can also be suppressed.

Restricting the movements of the semiconductor substrate 1 in the radialdirection is also helpful in positioning the light emitting end of thelight guide 10 and the light receiving portion 1a of the semiconductorsubstrate. That is to say, if the positions of the light emitting end ofthe light guide 10 and the light receiving portion 1a are registered andthen they are bonded with the adhesive agent 24, errors in dimensionamong parts resulted from the dimensional tolerances of the light guide10 or the like can be adjusted to realize precise positioning.

FIG. 4 is a plan view showing the semiconductor substrate 1 fixed to theprojection 6a. As shown in FIG. 4, the adhesive agent 24 is applied atintervals around the semiconductor substrate 1. In the projection 6a,through holes 6b passing through from the upper surface to the lowersurface of the projection 6a are provided at the positions where theadhesive agent 24 is not applied to. Returning to FIG. 1, thisestablishes communication between above and below the semiconductorsubstrate 1. As a result, the gases such as the oxidizing gas, steam,and the like produced in the housing can be exhausted through theexhaust spigot 11b provided above the semiconductor substrate 1, andfurther the gas in the housing can be replaced by the inert gas.

As shown in FIG. 1, notches (grooves) 4a and 4b for introducing thelight guide 10 are formed in the main electrode 4. The loss heatgenerated in the semiconductor substrate 1 is transmitted through themain electrodes 4 and 5 and radiated out of the device. To transmit theloss heat efficiently, it is desired that the volume of the cavityformed in the main electrode 4 by the notches 4a and 4b is as small aspossible. To satisfy this demand, as shown in FIG. 5 and FIG. 6, whichare respectively a sectional view and a bottom view of the mainelectrode 4, the shape of the notch 4b at the center of the mainelectrode 4 is not a cylindrical shape but a frustum of a cone, i.e., itis tapered.

This facilitates insertion of the light emitting end of the light guide10 and attachments thereof and increases the volume of the metal part ofthe main electrode 4 to improve the transmission efficiency of the lossheat. The shape of the notch 4b may be a hemisphere in place of afrustum of a cone, or it may take other shapes which have its openingarea increasing as it gets closer to the bottom. Though not shown in thefigure, the shape of the notch 4a is also preferably set so that itbecomes larger as it gets closer to the opening away from the bottom ofthe groove.

FIG. 7 is an enlarged front sectional view of the vicinity of thehorizontal light entering end in the light guide 10 which bends in theform of "L". A through hole for transmitting the light signals is formedin the horizontal direction in the insulation tube 6. A metal tube 40 isfixedly inserted in this through hole. An optical transmissive lightintroducing window 42 through which light signals from outside aretransmitted is airtightly bonded to this metal tube 40 through acircular ring like fixing jig 41. A tubular body 43 threadingly engagesthe inner side of the metal tube 40 to be fixedly inserted therethrough.

The tubular body 43 is formed of resin or metal, for example, with itsinside diameter somewhat larger than the diameter of the light guide 10so that they are not in contact with each other. The tubular body 43projects more inwardly than the inner side of the insulation tube 6.Even if the main electrode 4 in FIG. 1 turns in the assembling workbefore welding, the notch 4a will not directly abut on the light guide10 because of the existence or the tubular body 43. That is, the tubularbody 43 serves as a protection member for protecting the light guide 10.As the light guide 10 and the notch 4a do not abut on each other, damageof the light guide 10 caused by abutting is avoided, and displacement(positional slipping off) of the light emitting end of the light guide10 from the light receiving portion 1a of the semiconductor substratewill not be caused, either.

As shown in FIG. 7, an elastic tubular body 44 having flexibility, suchas silicone rubber system, is interposed between the tubular body 43 andthe light guide 10. The light guide 10 is flexibly supported by themetal tube 40 with this elastic tubular body 44 interposed therebetween.Accordingly, vibration, impact and the like applied from outside areabsorbed by the elastic tubular body 44, and the light guide 10 isprevented from being damaged by the vibrations, impact, etc.

Further, expansion and shrinkage of members such as the light guide 10and the like with repeated temperature change, i.e., temperature cycleare absorbed by the elastic tubular body 44. Accordingly, damage,fatigue and the like resulted from the thermal stresses produced by thetemperature cycle can also be prevented. Furthermore, it is advantageousin that the positioning of the light emitting end of the light guide 10is facilitated.

A reflection preventing film formed of silicon dioxide, for example,having a single layer or multiple layers is formed on the both surfacesof the light introducing window 42 by a method of vapor deposition orthe like. This suppresses reflection of light signals which will causetransmission loss of light signals and improves the transmissionefficiency. A material which can satisfactorily stand high temperaturewhen soldered is selected for the reflection preventing film, since theformation of the reflection preventing film is performed before thelight introducing window 42 is fixed to the fixing jig 41 by solderingor the like. A similar reflection preventing film is formed on both ofthe light entering end and the light emitting end of the light guide 10or on one of them to improve the transmission efficiency of lightsignals.

FIG. 8 is an enlarged front sectional view in the vicinity of the lightemitting end of the light guide 10. Two guide rings 50 and 51 are usedto normally position the light emitting end of the light guide 10 to thelight receiving portion 1a of the semiconductor substrate 1. The guiderings 50 and 51 are formed of resin or the like. The guide ring 50 has athrough hole formed at its center, into which the light guide 10 isinserted. Furthermore, the guide ring 50 fits to the outer periphery ofthe guide ring 51.

To fix the light emitting end of the light guide 10, the guide ring 51is first provided at a position concentric with the light receivingportion 1a of the semiconductor substrate 1 and then it is fixed withadhesive agent 52. After that, optical coupling agent 20 is put insidethe guide ring 51. Resin which has some fluidity before solidifying andmaintains some flexibility after thermally treated or left at ordinarytemperature and solidified, and which has optical transparency andrefractive index of about 1.3 to 1.5 is selected for the opticalcoupling agent 20. Silicone rubber system is suitable for this, forexample.

Before the optical coupling agent solidifies, the light emitting end ofthe light guide 10 is inserted into the optical coupling agent 20 andthe guide ring 50 with the light guide 10 previously inserted therein isfitted to the guide ring 51. As the guide ring 51 is fixed at thepredetermined position, the light emitting end of the light guide 10 isnaturally positioned above the light receiving portion 1a when the guiderings 50 and 51 fit to each other. Accordingly, light signals are surelytransmitted to the light receiving portion 1a of the semiconductorsubstrate 1.

As the optical coupling agent 20 has the flexibility, the expansion andshrinkage of the parts such as the light guide 10 due to the temperaturecycle are absorbed by the optical coupling agent 20. Accordingly, damageor the like of the light guide 10 caused by the thermal stressesresulted from the temperature cycle is prevented.

Examples of Modifications

(1) In the preferred embodiment described above, the thermalcompensating plate 3 and the main electrode 5 are coupled through asingle pin located at the center. The thermal compensating plate 3 andthe main electrode 5 may be coupled at a plurality of positions by usinga plurality of pins in place of the single pin. In this case, at leastone of the thermal compensating plate 3 and the main electrode 5 ispreferably coupled by pins with some play so that the thermal distortioncaused by the difference of thermal expansion coefficients between thethermal compensating plate 3 and the main electrode 5 can be absorbed.

(2) The projection 6a does not necessarily have to be formed on theentire periphery of the inner wall of the insulation tube 6. Forexample, they may be formed at four positions along the entire peripheryat equal intervals. This structure can also stably support thesemiconductor substrate 1. To support it more stably, however, it ispreferable to form the projection 6a around the entire periphery.

(3) The structure is also possible where the projection 6a is notprovided on the inner wall of the insulation tube 6 and thesemiconductor substrate 1 is fixed on the inner wall of the insulationtube 6 through the insulation resin (resin for protection) 23. In thiscase, the insulation resin 23 may abut on the inner wall of theinsulation tube 6 with elastic restoring force of the insulation resin23 itself without adhesive agent applied thereto to be supported by theinsulation tube 6. Otherwise, adhesion may be applied so that theinsulation resin 23 does not slip off in the axial direction of theinsulation tube 6.

Further, the insulation resin 23 does not necessarily have to beattached around the entire periphery of the semiconductor substrate 1.For example, it may be attached at four positions along the entireperiphery at equal intervals. To support it more stably, however, it ismore preferable that the insulation resin 23 is formed around the entireperiphery.

(4) The input end of the light guide 10 may be directly provided intothe through hole formed in the insulation tube 6 only through theelastic tubular body 44 without the metal tube 40 and the tubular body43. This structure can also prevent the damage of the light guide 10caused by vibrations, impact and the like applied from outside andtransmitted to the light guide 10.

(5) Although the two guide tings 50 and 51 are used in the preferredembodiment described above, a single guide ring 51 may be used to fixthe light emitting end of the light guide. In the device with thisstructure, the optical coupling agent is put in the guide ring 51 andthe light emitting end of the light guide 10 is inserted into theoptical coupling agent before it solidifies. At this time, the lightguide 10 is guided by the guide ring 51 to be positioned at the mostsuitable position.

(6) The structure of positioning the thermal compensating plate and thelike produce the same effects when they are applied to the electrictrigger type thyristors, such as the GTO thyristors, or semiconductordevices such as diodes not only to the light trigger type thyristors. Inthe electric trigger type thyristor, a signal transmission path fortransmitting electric control signals is provided in place of the lightguide 10, and the notches 4a, 4b, the tubular body 43, etc. produce thesame effects as those in the above-described embodiment.

While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore understood that numerous modifications andvariations can be devised without departing from the scope of theinvention.

What is claimed is:
 1. A pressure contact type semiconductor device,comprising a semiconductor substrate and an insulation tube surroundingthe semiconductor substrate, said insulation tube having a projectionformed on an inner wall thereof and projecting inwardly, saidsemiconductor substrate being fixed to said projection.
 2. The pressurecontact type semiconductor device according to claim 1, wherein saidsemiconductor substrate is fixed to said projection by using an adhesiveagent.
 3. The pressure contact type semiconductor device according toclaim 1, wherein said semiconductor substrate is fixed to saidprojection through a protection resin provided on the periphery of thesubstrate.
 4. The pressure contact type semiconductor device accordingto claim 1, wherein said projection is formed on the entire periphery ofsaid inner wall.
 5. The pressure contact type semiconductor deviceaccording to claim 4, wherein inside of said insulation tubeaccommodating said semiconductor substrate is airtight from outside anda through hole is formed in said projection.